The invention concerns a laser with at least two electrode tubes, whose axes run rectilinearly and one of which is the inner electrode tube and is arranged inside the other outer electrode tube, forming an intermediate annular space serving as the discharge space, and with a cooling device with a wall that has at least one inner coolant line placed inside the inner electrode tube and/or at least one outer coolant line with a wall placed outside the outer electrode tube, whereby the inner and/or outer coolant lines have a heat-transfer connection on their walls with the electrode tube assigned to them. The invention also concerns a process for producing this type of laser with at least one plastically deformable inner coolant line and/or at least one plastically deformable outer coolant line. Finally, the invention concerns a device for carrying out the production process just mentioned.
As is known, the laser process that takes place in the discharge space of a laser is associated with the development of heat, which must be taken away so the whole arrangement can function. This heat can be discharged by cooling the laser electrodes.
A corresponding electrode of the type mentioned at the beginning, in the form of a laser with a coaxial design, is disclosed in DE-U-299 12 670. The cooling device of this laser has an inner cooling coil as the inner coolant line and an outer cooling coil as the outer coolant line. Both cooling coils are formed by a round tube curved coaxially with the electrode tubes, which is molded with linear contact to the generating surface of the electrode tube assigned to it parallel to the axis facing it. When the previously known laser is produced, the round tubes for the coolant lines are curved into coils by mandrels. The diameters of the mandrels are chosen so that the inner cooling coil has an outer diameter that corresponds to the inner diameter of the inner electrode tube and the outer cooling coil has an inner diameter that corresponds to the outer diameter of the outer electrode tube. Then, the inner cooling coil is pushed inside the inner electrode tube, and the outer cooling coil is pushed onto the outer casing of the outer electrode tube. In the case of a non-generic laser design previously known from practical applications, coil-like grooves are milled directly into the walls of the electrode tube and are used as paths through which the coolant flows when the laser is in operation.
The goal of this invention is to create a laser that guarantees effective cooling of the discharge space between the electrode tubes with structurally simple technical production measures. Another goal of the invention is to provide a corresponding simple production process and a device for carrying out this type of simple production process.
It has now been found that the foregoing and related objects may be readily obtained in a laser tube assembly including at least two rectilinear coaxial electrode tubes spaced apart to provide an annular space therebetween serving as the discharge cavity for the lasing gas. At least one coolant line extends about the surface of an electrode tube spaced from the discharge cavity and having a first surface in heat transfer assembly with the electrode tube assigned to it. A support device is provided on the other surface of the coolant line.
Generally, coolant lines are provided about the outer surface of the outer electrode tube and about the inner surface of the inner electrode tube, and support devices are provided on the outer surface of the outer coolant line and on the inner surface of the inner coolant line.
The support devices are cylindrical pipes with axes coaxial with that of the electrode tubes. The inner coolant line is kept in surface contact with the inner electrode tube by means of the inner support device and the outer coolant line is kept in surface contact with the outer electrode tube by means of the outer support device.
Preferably, said coolant lines are provided by helical coils of tubing which have a non-round cross section providing a surface portion conforming to and in surface contact with the wall of said electrode tubes to improve heat transfer. Conveniently, the support devices are cylindrical pipes and the coolant lines are in surface contact with the pipes.
The laser is produced by a process in which at least two rectilinear and coaxial electrode tubes are assembled in spaced apart relationship to provide an annular space therebetween serving as the discharge cavity. A cooling device is included and includes at least one coolant line extending about the surface of the electrode tube spaced from the discharge cavity, and a support device is provided about the surface of the coolant line spaced from its associated electrode tube. The cooling line has a plastically deformable wall, and a fluid under pressure is provided in the coolant line to deform the wall of the coolant line plastically into heat exchange contact with the assigned electrode tube or a surface that has a heat transfer connection with it.
Desirably, the wall of the coolant line are softened before it is subjected to deformation by the fluid under pressure. The softening of the cooling line is effected by heating, and preferably by annealing.
Preferably, the inner coolant line and outer coolant line have support end pieces and the walls of the inner coolant line and the walls of the outer coolant line are softened only in the area between the support end pieces before being acted on by the inner deformation pressure.
The fluid under pressure may be the medium later used as a coolant. Preferably, the coolant lines have a rectangular or oval cross section before being acted upon by the fluid under pressure. The support devices may remain as a part of the laser after the laser is produced.
By means of the inner and/or outer support device in patent claim 1, the inner and outer coolant lines are kept in close contact which is favorable for effective heat transfer with the assigned electrode tube directly or with a surface that in turn has a heat-transfer connection with the electrode tube in question. The process measures of pressure deformation allows the close contact sought for effective heat transfer between the inner and outer coolant lines and the assigned electrode tubes or assigned surfaces to be made in a way that is technically simple to produce. This makes it possible, in particular, to adjust the shape of the walls of the coolant lines by corresponding plastic deformation to the shape of the opposing electrode surface being cooled and thus produce a large surface area of close contact between coolant lines and the surfaces opposite them. This is a special advantage in the case of coolant lines whose cross section before the plastic deformation mentioned deviates somewhat from the ideal shape as a result of tooling-related deformation. In the sense of the invention, after the respective coolant line is deformed and its shape stabilized, the inner and outer support devices can remain on the laser or can be removed from the laser.
The use of an inner support tube as the inner support device and an outer support tube as the outer support device is recommended, since this ensures effective support of the coolant lines over a large surface on the side away from the accompanying electrode tubes and thus also especially effective placement of that coolant line on the opposite surface used for heat transfer.
The plastic deformation of the inner and/or outer coolant line is basically limited to the part of the line between the support end pieces of the coolant lines. The end pieces of the coolant lines mentioned can therefore be used without major prior tooling as connecting supports for supplying the laser with coolant.
If the deformation pressure for plastic deformation of the coolant lines is produced by means of a pressurized medium, which, depending on its type, is used as a coolant in later laser operation, then the expensive measures for cleaning the coolant lines after their deformation and before the laser is put into operation are unnecessary.
The process of the invention is very simple to design using coolant lines that have a rectangular or oval cross section before they are acted on with the inner deformation pressure. Before these types of coolant lines are deformed, if they are aligned in relation to the accompanying opposite surface used for heat transfer in such a way that the greatest possible surface area of their walls extends parallel to the opposite surface in question, then it takes only a relatively slight plastic deformation of the coolant lines for close contact with the surface being cooled over a large area.
The support devices can be used directly as support devices for the coolant lines of the finished laser, so it is not necessary to disassemble the support devices of the production jig. This is particularly significant since the coolant lines act on the support devices in their plastic deformation and their disassembly can consequently be difficult.